A conventional strobe device to be used for shooting a still picture or a moving picture includes a reflective lampshade (reflector) for reflecting light, radiated from a discharge tube, toward an object. The light radiated from the center of the discharge tube (glass bulb) travels in every direction (radiated from the entire circular direction of the discharge tube), so that an opening of the reflective lampshade should be large enough for this light to be condensed within an irradiation range. This large opening has prevented the strobe device from being downsized.
When the light radiated from the discharge tube is reflected on the reflective lampshade, the light radiated oppositely to the object (existing on the front side) repeats transmissions through the glass bulb, of which refractive index is greater than that of the air, and reflections on the reflective lampshade. An amount of light thus decreases in every transmission and reflection.
An optical member is provided to the strobe device in addition to the reflective lampshade for improving an efficiency of light condensation. However, this strobe device has a possibility that the amount of light further decreases because the light having undergone the reflections on the reflective lampshade is condensed with the optical member having a different refractive index (refer to, e.g. Patent Literature 1).
The inventors of the present invention address the problem discussed above and propose a strobe device that can be downsized and prevent an amount of light from decreasing caused by light radiation outside the irradiation range. This strobe device includes reflective film formed on outer peripheral surface of a glass bulb and a light transparent section, where no reflective film is formed, formed on a front side of the outer peripheral surface of the glass bulb.
On top of that, the inventors have found out that the positional relation described below is an important factor for increasing an efficiency of light emission by collecting the dispersing light radiated from the light transparent section of the foregoing discharge tube.
The positional relation exists between the light transparent section, a reflective curve inside the optical member, and the center of the discharge tube (center axis of the glass bulb).